Navigating in a 3D world - is the brain's map of space actually flat? Abstract: Understanding how the brain constructs a neural map oflarge-scale navigable space has been a major goal of neuroscience in thepast few decades. This is partly because space is an excellent modelsystem with which to study how "knowledge" structures are constructed byby the brain, and partly because the map seems to form the scaffold uponwhich episodic memories are laid down - understanding the map willtherefore help us understand memory and amnesia. Research up until recently has focused on flat, two-dimensional (2D)environments but the real-world is 3D. Navigating in three dimensionsposes unique problems that are not present in two and it is not knownhow, or even if, the brain solves this complex representationaltask. This talk will present both theoretical musings and research datafrom behavioural obsrvations and single neuron recordings made in ratsthat suggest that the vertebrate map of space is planar rather thanvolumetric - that is, it is locally flat. The advantages and limitationsof a flat map of space will be explored.